Guided Lessons

# Multi-Digit Multiplication Strategies

Facilitate an exploration and comparison of multiplication strategies for your students to see the variety of ways to solve the same problem. Use this lesson on its own or teach it prior to the lesson Multiplication: Musical Chairs.
This lesson can be used as a pre-lesson for theMultiplication: Musical ChairsLesson plan.

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This lesson can be used as a pre-lesson for theMultiplication: Musical ChairsLesson plan.

Students will be able to quickly multiply two- and three-digit numbers using multiplication strategies.

##### Language

Students will be able to compare multiplication strategies using discussion prompts and sentence stems/frames.

(5 minutes)
• Show students a blank Frayer Model and demonstrate how to complete the model with the word Strategy. Write the definition, a sentence, an example, and a non-example, and draw an image. Emphasize that the term strategy can apply to many different aspects of life, including board games and sports, but for the purpose of this lesson, we will focus on its meaning as it relates to maths and solving maths problems.
• Write "Multiplication Strategies" on a piece of chart paper. Lead students in a brainstorm of all the different strategies they know to solve multiplication of two-digit numbers using the problem 8 x 34Or 12 x 26Depending on your students' maths level.
• Co-create a list of strategies with students and include an example of how to solve the example problem with the strategy. Students may include strategies such as mental maths, partial products, standard algorithm, decomposition (breaking apart numbers), area model, or lattice.
• If students are unsure of the process for any of the strategies mentioned in the list, spend some time reviewing the steps to make sure students are familiar with them. Note: Students are also welcome to share their own strategies for multiplication that do not fall under any of the strategies named earlier. It is not essential for AllStrategies to be represented in the list as the focus of the lesson is on students practising their verbal comparison skills when it comes to maths strategies.
(6 minutes)
• Tell students they will review some helpful vocabulary to know as they compare multiplication strategies.
• Hold up the vocabulary cards or display them on the document camera. Read each word aloud and invite a student to read its definition.
• Place students into partnerships and have them discuss their background knowledge and exposure to the word by asking the following questions: Have you heard of this word before? Can you explain what it means in your own words? How have you used this word in the past?
• Ask some pairs of students to share key points from their discussion.
• Hand out a Glossary worksheet to each student. Have them write "More Information" in the last, empty column in the far right of the Glossary worksheet. Tell students to work with their partner to add additional information in this column. Tell students that they could draw a picture or symbol, write a synonym in their home language (L1), or write a sentence using the word. Anything they choose to add to this column should help them further understand the meaning of the word on a deeper level.
• Have some students read aloud the information they added to the Glossary worksheet.
(12 minutes)
• Model on the document camera or on chart paper how to solve 24 x 15Using two of the strategies from the list created in the introduction. Think aloud as you compare the solution strategies. For example, if comparing the partial product and decomposition strategies, you could say, "Both strategies involve multiplying parts of the factors so that they are easier numbers to work with. Both strategies require us to add partial products at the end to find the answer. The partial product strategy means you have to be able to break down the factors into expanded form based on place value but the decomposition strategy lets us break down the factors into any easy number that works."
• Write the following word problem on the board and read it aloud: Martin has 6 bags of marbles. Each bag has 22 marbles. How many marbles does he have in all?
• Distribute whiteboards and markers to each student. Have students work with the same partner, and instruct them to discuss ways to solve the problem. Then, have them solve the problem on the whiteboards using a strategy of their choice.
• Place students in a group of four (make sure the two pairs used different strategies) and have them compare their solution strategies using the following discussion prompts and sentence frames/stems as a guide:
• Which strategy did you use to solve the problem and why? (We used the ____Strategy because...)
• How are the strategies similar? (The strategies are similar in that they both...)
• How are the strategies different? (The ____Strategy is... while the ____Strategy is...)
• Invite a few students to share their solution strategies and comparisons with the whole class.
• Record students' responses on a piece of chart paper.
(10 minutes)
• Give students a sheet of blank copy paper. Write a problem on the board, "The city ordered 32 boxes of flowers to be planted along the highway. Each box contains 24 flower plants. How many plants are there in all?"
• Tell students to fold their copy paper in half and solve the problem independently using two different strategies. Encourage students to look at the list of strategies and examples to choose from. Remind them that they will need to be able to explain the two strategies they use.
• Circulate to assist students as needed.
• Place students with a new partner, and have them share their work. Instruct them to compare and contrast their solution strategies orally with their classmate.
• Give students the following sentence frames to help them discuss the solutions:
• I solved the problem using the ____And ____Strategies because...
• First, I... Then, I... Finally, I...
• My two strategies are similar in that they both...
• The two strategies are different in that the first is... and the second is...
• I prefer the ____Strategy because...
• Ask a few sets of pairs to share some interesting and important discussion points with the whole class.

Beginning

• Provide students access to home language resources, such as bilingual glossaries or online dictionaries, to help them make more meaning of the terms used in the class.
• Pair students with more advanced students or other ELs who speak the same home language (L1) for partner activities and group work.
• Create and display a word/phrase bank with helpful terms from the lesson for students to refer to, with images if applicable.
• Have students restate the main learning points of the lesson before doing the group work.

• Have students describe their maths processes without relying on the sentence stems/frames.
• Encourage students to rephrase the directions throughout the lesson.
(4 minutes)
• Have students flip their copy paper over and instruct them to choose any strategy to solve this multiplication problem: 43 x 11. Remind students to show their work and be prepared to explain their maths thinking.
(3 minutes)
• Invite students to share their solution to the formative assessment with a peer.
• Call on a few students to share their solutions on the document camera for the whole group.
• Congratulate students on their hard work solving multi-digit multiplication problems and using their verbal skills to compare and contrast various multiplication strategies. Tell students that it is always helpful to know more than one way to solve a problem.